Refill cartridge for a stick and a method for filling the cartridge

ABSTRACT

The invention is associated with a refill cartridge for a stick which applies product by rubbing onto a surface, comprising a tube-like element, which is designed to be tightly closed at both ends and of which one end is designed to fit tightly onto a tube element of the stick; a longitudinally displaceable plunger with a screwthreaded bore--onto which a screwthreaded spindle of the adhesive stick projecting from the tube element is designed to be screwed--being non-rotatably guided in the tube-like element; and the tube-like element being filled with a product which bears against the plunger at one end and, the product in an extension of the screwthreaded bore, is formed throughout with a bore in which the screwthreaded spindle engages when the refill cartridge is fitted onto the stick. The bore in the product is formed via the tube-like element being releasably closed at its free end by a sealingly fitted cap-like closure element, the cap-like closure element being internally formed with a pin-like projection which fills the intended area of the bore extending throughout the product in a liquified state. After the product solidifies, removal of the cap and its associated pin-like projection leaves the bore fully formed in the product.

BACKGROUND

1. Field of the Invention

This invention relates to a refill cartridge for a stick which appliesproduct by rubbing onto a surface, such as an adhesive stick.

2. Discussion of Related Art

Refill cartridges of this type and a corresponding method for fillingthem are known from applicants' DE 41 20 969 A1 and also from DE 41 16581 A1. They are particularly suitable for refilling adhesive sticks,but also other sticks which apply product by rubbing onto a surface,such as deodorant sticks, lipsticks, lubricant sticks, shaving soapsticks or crayons. The main advantage of these refill cartridges isthat, when the stick is empty, its key non-consumable elements can berepeatedly reused by quasirefilling of the stick with a refillcartridge, for which purpose the initially closed refill cartridge isfitted onto and secured to the stick, the screwthreaded spindle of thestick being introduced into the refill cartridge and screwed into theplunger so that it can then engage in the bore formed over the entirelength of the product of the refill cartridge.

Although a refill cartridge of the type in question has considerableadvantages, it has been found that the production and filling of such arefill cartridge with initially liquid product involve disadvantages inview of the need to form a bore throughout the product to receive thescrewthreaded spindle. Thus, in the method according to DE 41 20 969 A1,the empty refill cartridge closed at its bottom end is initiallyintroduced into a mold in which a pin extending over the mold--forreceiving the screwthreaded bore of the plunger and for forming the boreextending throughout the product--is arranged at the bottom of the moldconcentrically of its longitudinal axis. The product is then poured inand, after the product has solidified, the pin forming the bore in theproduct has to be removed. The refill cartridge then has to be tightlyclosed at both ends to ensure that the product does not come intocontact with the surrounding air.

SUMMARY OF THE INVENTION

Accordingly, the problem addressed by the present invention is to enablea refill cartridge of the type in question to be produced and filledmore easily and to remain satisfactorily sealed after filling.

In a refill cartridge of the type mentioned at the beginning, thesolution provided by one embodiment of the invention includes atube-like element releasably closed at its free end by a sealinglyfitted cap-like closure element, the cap-like closure element beinginternally formed with a pin-like projection which fills the boreextending throughout the product.

A refill cartridge designed in this way is much easier to make and tofill. Thus, the product may initially be poured in liquid form into therefill cartridge closed at its bottom end, after which the cap-likeclosure element is sealingly fitted, with the pin-like projectionforming the desired bore in the product while it is still in the liquidstate. The length of the pin-like projection is such that a boreextending over the entire length of the product is formed. When therefill cartridge is used by the consumer, the cap-like closure elementmerely has to be removed from the refill cartridge, thus uncovering thebore extending through the solid product.

In one particularly advantageous embodiment, the length of the pin-likeprojection is such that the free end thereof engages at least locally inthe screwthreaded bore of the plunger in the fully fitted state of thecap-like closure element. This ensures that even the screwthreaded boreof the plunger is substantially free from product so that, when therefill cartridge is used, the screwthreaded spindle of the pin canreadily be screwed in.

In another particularly advantageous embodiment, the cap-like closureelement and/or the outer receiving zone of the tube-like element for thecap-like closure element is/are provided with co-operating, encirclingstop means which are designed in such a way that, before the stop meanscross over one another, the pin-like projection penetrates fully throughthe product. In this way, the required full-length screwthreaded borecan be produced in two stages by initially loosely applying the closurecap with its pin-like projection after filling product for the purposeof air equalization, with the pin-like projection being centered by thecap-like closure element and by the entry of the tip of the pin-likeprojection into the screwthreaded part of the plunger. After the fillingproduct has cooled, a sealing closure and, at the same time, furtherpenetration of the pin-like projection into the screwthreaded part ofthe plunger are achieved by application of pressure to the cap-likeclosure element and by crossing of the stop means over one another, withsmall amounts of filling in the region of the screwthread bore beinglaterally displaced past the tip of the pin-like projection.

In another particularly advantageous embodiment, the cap-like closureelement is flexible and the pin-like projection is rigid, in order toestablish an effective seal between the cap-like closure element and thetube-like element of the refill cartridge and, on the other hand, toenable the pin-like projection to penetrate satisfactorily through theproduct.

To avoid accumulations of material, the cap-like closure element and thepin-like projection are preferably in two parts designed to bereleasably interconnected.

Another particularly advantageous embodiment is characterized in thatthe screwthreaded bore of the plunger and/or the associated opening inthe bottom of the tube-like element are covered by a protective film orthe like. The protective film or thin zone in the bottom of thecontainer seals off the refill cartridge from outside, while theprotective film in the region of the screwthreaded bore of the pistonensures that when the liquid product is poured in, it cannot passcompletely into and thus block the bore.

Depending on the filling materials, the free end of the pin-likeprojection may advantageously be pointed, conical or stepped.

In another advantageous embodiment, the tube-like element is externallyprovided with at least one longitudinal groove. This longitudinal grooveco-operates with a fillet internally provided on the tube element of thestick and affords protection against rotation, as known from FIG. 6 ofDE 41 16 581 A1.

To solve the problem stated at the beginning, the invention alsoprovides a method for filling a refill cartridge of the type describedin the foregoing with initially liquid and subsequently solidifyingproduct, in which product is poured into the plunger-equipped refillcartridge closed at its bottom end. This method being characterized inthat, after the product has been poured in and before it solidifies, thecap-like closure element is fitted onto the corresponding end of thetube-like element in such a way that the pin-like projection penetratesfully into the liquid product to form a bore.

In one particularly advantageous embodiment, the cap-like closureelement is initially fitted onto the tube-like element to such an extentthat the free end of the pin-like projection only projects into theregion of the screw-threaded bore of the plunger and, aftersolidification of the product, the cap-like closure element is fully andsealingly fitted onto the tube-like element by crossing of the stopmeans over one another. In this way, air equalization, i.e. an outwardescape of air, can initially occur during filling, following which therefill cartridge is tightly closed after solidification of the product.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail in the following withreference to the accompanying drawings, in which like items areidentified by the same reference designation, wherein:

FIG. 1 is a section through a refill cartridge according to oneembodiment of the invention during fitting onto a stick.

FIG. 2 shows the refill cartridge during filling.

FIG. 3 shows the refill cartridge after filling during the fitting of acap-like closure element for one embodiment of the invention.

FIG. 4 shows the refill cartridge in its fully closed state.

FIG. 5 shows an embodiment of the cap-like closure element.

FIGS. 6 and 7 show embodiments of the free end of the pin-likeprojection of the cap-like closure element.

FIG. 8 shows details of the longitudinal grooves and longitudinalfillets of the tube element and refill cartridge for an embodiment ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

A refill cartridge according to the invention for a stick which appliesproduct by rubbing onto a surface is globally denoted by the reference 1in the drawings. In the illustrated embodiment, the refill cartridge 1is intended for an adhesive stick, forming part of the adhesive stickafter fitting or joining thereto. Accordingly, the adhesive stick as awhole, including the refill cartridge 1, is denoted by the reference 2.Besides adhesive sticks, a refill cartridge according to the inventionis also suitable for other product sticks designed to apply a smallamount of product onto a surface by rubbing on that surface, for exampledeodorant sticks, lipsticks, lubricant sticks, shaving soap sticks orcrayons. In the interests of clarity, however, the following descriptionrefers solely to an adhesive stick or adhesive product, but is not meantto limit the invention thereto.

Apart from the refill cartridge 1, which is part of the adhesive stick2, the adhesive stick 2 comprises a tube element 3 with a continuousbase 4 which merges into an encircling snap-action fastening 5 forreceiving a knurled nut 6 with a screwthreaded spindle 7 projectingupwards from the tube element 3. The tube element 3 widens upwardstowards one end. This region is denoted by the reference 3a and isprovided internally with an internal screwthread 8 for securing thecorresponding end of the refill cartridge 1, for which purpose therefill cartridge 1 is provided with a corresponding outer thread 9.

The refill cartridge 1 itself comprises a tube-like element 1 with asubstantially continuous base 11 which is centrally provided with a thinzone, a push-through zone or the like denoted by the reference 22 inFIG. 2. Arranged inside the refill cartridge 1 is a longitudinallydisplaceable plunger 12 with a screwthreaded bore 13 which isnon-rotatably guided in the tube-like element 10 (not shown in detail),the screwthreaded bore 13 corresponding with the outer screwthread 14 ofthe screwthreaded spindle 7 of the adhesive stick 1. Above the plunger12, the tube-like element 10 of the refill cartridge 1 is filled with anadhesive product 15 which is provided over its entire length with a bore16 that forms an extension of the screwthreaded bore 13 of the plunger12.

As can best be seen from FIGS. 3 to 5, the refill cartridge 1additionally comprises a cap-like closure element 17 designed to befitted onto the free end of the tube-like element 10 from outside. Thecap-like closure element 17 is internally provided with a pin-likeprojection 18 of which the length is such that the free end 19 of thepin-like projection 18 engages at least locally in the screwthreadedbore 13 of the plunger 12 in the fully fitted state of the cap-likeclosure element 17.

The cap-like closure element 17 and the outer receiving zone of thetube-like element 10 for the cap-like closure element 17 are providedwith co-operating encircling stop means 20,21 which, in the embodimentillustrated, are formed by snap-action beads. However, the stop meanscould also assume any other form, for example a screw connection. Thefunction of the stop means 20,21 is to enable the cap-like closureelement 17 to be initially fitted onto the tube-like element 10 in afirst fitting position (FIG. 3) and, after the stop means 21 havecrossed over the stop means 20, to be fully and tightly fitted onto thetube-like element 10.

Before the refill cartridge 1 is filled, it is preferably closed twiceat its bottom end, i.e. once by means of the push-through zone or thinzone 22 and then by a protective film 23 or the like which covers thescrewthreaded bore 13 of the plunger 12.

After the plunger 12 has been introduced into the tube-like element 10,the adhesive product 15 is poured in liquid form into the tube-likeelement 10 until the tube-like element 10 is substantially full. Theprotective film 23 in the region of the screwthreaded bore 13 preventsthe adhesive from completely filling and blocking the screwthreaded bore13.

While the adhesive 15 is still liquid, the cap-like closure element 17is fitted onto the tube-like element 10 of the refill cartridge fromabove, as shown in FIG. 3, in such a way that the stop means 20,21 comeinto contact with one another without crossing so that the sealing sidewall region 17a of the cap-like closure element 17 does not yet seal offthe refill cartridge 1 at its upper end. At the same time, the pin-likeprojection 18 of the cap-like closure element 17 penetrates centrallyinto the liquid product 15 and, acting as a core, forms the desired bore16 throughout the product 15. Through the choice of a suitable lengthfor the pin-like projection 18, the free end 19 of the pin-likeprojection penetrates slightly into the screwthreaded bore 13 and iscentered therein.

When the adhesive 15 has hardened sufficiently, the cap-like closureelement 17 is fully applied by crossing of the stop means 20 over thestop means 21 so that, on the one hand, tight closure of the upper endof the refill cartridge 1 is guaranteed, because the stop means 20,21bear tightly against one another, and on the other hand the free end 19of the pin-like projection 18 penetrates so far into the screwthreadedbore 13 that any residues of adhesive present there are pushed aside.

Accordingly, the refill cartridge 1 is ready for use through formationof the bore 16 extending throughout the product 15 and may be marketedin this form.

If, now, the refill cartridge 1--as part of an adhesive stick 2--isfixed to the adhesive stick 2, as shown in FIG. 1, the cap-like closureelement 17 is removed and the tube-like element 10 of the refillcartridge 1 is screwed onto the tube element 3 of the adhesive stick 2.At the same time, the screwthreaded spindle 7 of the adhesive stick 2,after penetrating the thin zone 22 and the protective film 23, entersthe screwthreaded bore 13 of the plunger 12 of the refill cartridge 1 sothat the product 15 is able to pass over screwthreaded spindle 7 withoutdifficulty.

A closure cap may then be applied to the tube-like element 10 at itsupper end in order to seal off the tube-like element 10.

In one particular embodiment, the cap-like closure element 17 itself maybe used as the closure cap providing, as shown in FIG. 5, the cap-likeclosure element 17 and the pin-like projection 18 are in two partsreleasably joined to one another. To this end, the cap-like closureelement 17, as shown in FIG. 5, is internally provided with a centralcylindrical projection 24 with an encircling stop bead 25 onto which thehollow pin-like projection 18 is designed to fit via a correspondinginner bead 26. If, now, the pin-like projection 18 is removed from thecap-like closure element 17, the cap-like closure element 17 may be usedas a closure cap for the adhesive stick 2.

The cap-like closure element 17 is preferably made of a flexibleplastic, while the pin-like projection 18 is rigid which guaranteeseffective sealing of the tube-like element 10 by the cap-like closureelement 17, and satisfactory formation of the bore 16 in the adhesiveproduct 15 by the pin-like projection 18.

Depending on the products used, the free end 19 of the pin-likeprojection 18 of the cap-like closure element 17 may assume variousforms. In the embodiments shown in FIGS. 2 to 5, the free end 19 ispointed whereas, in the embodiment shown in FIG. 6, the free end 19a isrounded. In the embodiment shown in FIG. 7, the free end 19b is stepped.

In addition to the embodiment shown in FIG. 1, the tube-like element 10of the refill cartridge 1 may be externally provided with longitudinalgrooves 31 (see FIG. 8) which co-operate with longitudinal fillets 32 onthe inside of the tube element 3 and stop the tube-like element 10 fromrotating in the tube element 3, as known in detail from DE 41 16 581 A1and described therein with reference to FIG. 6 of the drawings. Throughthis additional anti-rotation measure, which has not been shown in thedrawings, the refill cartridge 1 can be introduced into the tube element3 without difficulty.

The invention is not of course confined to the illustrated embodiments.Further embodiments of the invention are possible without departing fromthe basic concept. For example, the connection between the cap-likeclosure element 17 and the tube-like element 10 of the refill cartridge1 may assume a different form and may even consist, for example, of ascrew connection or the like. Such further embodiments, which may berecognized by those of skill in the art, are meant to be covered by thespirit and scope of the appended claims.

What is claimed is:
 1. A refill cartridge for a stick applicator whichapplies product by rubbing the product onto a surface, such as with anadhesive stick, comprising:said refill cartridge including:a hollowtubular body for containing said product; a longitudinally displaceableplunger including a centrally located screwthreaded bore, said plungerbeing initially retained within an opening in a bottom end of saidtubular body; a cap-like closure element internally formed with acentrally located elongated pin-like projection, whereby when saidclosure element is secured to a top end of said tubular body for closingoff the same, said pin-like projection extends through said product,thereby forming an elongated central bore through said product; saidstick applicator including:a base member having an upper portionconfigured to receive and tightly be secured to the bottom of saidtubular body of said refill cartridge; a centrally located screwthreaded spindle protruding from said upper portion for screwinginitially into said screwthreaded bore of said plunger, and into thecentral bore of said product after said cap-like closure element and itspin-like projection are removed from the top of said tubular body ofsaid refill cartridge; and means in a lower portion of said base memberfor rotating said screwthreaded spindle in a direction for moving saidplunger toward the open end of said tubular body to force a desiredportion of said product therefrom.
 2. A refill cartridge as claimed inclaim 1, wherein the length of the pin-like projection is such that thefree end thereof engages at least locally in the screwthreaded bore ofthe plunger in the fully fitted state of the cap-like closure element.3. A refill cartridge as claimed in claim 1, wherein the cap-likeclosure element, and the outer surface of the tubular body proximate itstop end receptive of the cap-like closure element are provided withcooperating, encircling stop means which are designed in such a waythat, before the stop means cross over one another, the pin-likeprojection penetrates fully through the product.
 4. A refill cartridgeas claimed in claim 1, wherein the cap-like closure element is flexibleand the pin-like projection is rigid.
 5. A refill cartridge as claimedin claim 1, wherein the cap-like closure element and the pin-likeprojection are in two parts designed to be releasably interconnected. 6.A refill cartridge as claimed in claim 1, wherein the screwthreaded boreof the plunger and the opening in the bottom of the tubular body arecovered by a protective film.
 7. A refill cartridge as claimed in claim1, wherein the free end of the pin-like projection is pointed.
 8. Arefill cartridge as claimed in claim 1, wherein the tubular body isprovided with at least one longitudinal groove proximate its bottom end.9. A refill cartridge as claimed in claim 1, wherein the free end of thepin-like projection is rounded.
 10. A refill cartridge as claimed inclaim 1, wherein the free end of the pin-like projection is stepped. 11.A method for filling a refill cartridge with initially liquid andsubsequently solidifying product, said refill cartridge including ahollow tubular body for containing said product, a longitudinallydisplaceable plunger including a centrally located screwthreaded bore,said plunger being initially retained within an opening in a bottom endof said tubular body, a cap-like closure element internally formed witha centrally located elongated pin-like projection, whereby when saidclosure element is secured to a top end of said tubular body for closingoff the same, said pin-like projection extends through said productthereby forming an elongated central bore through said product; saidmethod including the steps of:pouring product into the plunger-equippedrefill cartridge closed at its bottom end, and after the product hasbeen poured in and before it solidifies, fitting the cap-like closureelement onto the top end of the tubular body in such a way that thepin-like projection penetrates fully into the liquid product to form abore.
 12. A method as claimed in claim 1, said fitting step furtherincluding the step of:the cap-like closure element onto the top end ofsaid tubular body, before solidification of said product, to such anextent that the free end of the pin-like projection only projects intothe region of the screwthreaded bore of the plunger.